Conventionally, a pressure-sensitive adhesive film has been widely used in various industrial fields and has been obtained by providing a pressure-sensitive adhesive layer on the surface of a substrate.
For example, it has been proposed that an aqueous dispersion type pressure-sensitive adhesive composition having a concentration of solid content of 47 weight % obtained by adding an acrylic thickener to an emulsion of an acrylic copolymer is applied onto a release film to be thereafter dried, so that a pressure-sensitive adhesive layer is obtained (ref: for example, the following Patent Document 1).